Like that, no, it's incorrect. Like that it would render into English as something like "my pulse of my heart".

If you separated it with a comma, "mo cuisle, mo chroí" it would translate as "my pulse, my heart". To simply say "Pulse of my heart" you would say, in Irish, "cuisle mo chroí". In either case, you wouldn't say this to the person in question, rather, you would say it about them.

If you want to address the person you would use the vocative, "a cuisle mo chroí", "Oh pulse of my heart".